Alternative Fuels Analyzer

ABSTRACT

A process for preparing alternative fuels so that it is acceptable for use in cement plants and other manufacturing processes is detailed. This includes a material analyzer that can detect trace contaminants in alternative fuels. This new analyzer, combined with an associated method of processing the alternative fuels allows users to blend the fuel to ensure that it is acceptable for plant operations.

TECHNICAL FIELD

The present invention relates generally to in-line analyzers, and isdirected to an in-line analyzer for alternative fuels.

BACKGROUND

In line Prompt Gamma Neutron Activation Analysis (PGNAA) analyzers arein wide use throughout the coal, cement, and minerals industries. Thesesystems are used for measuring bulk material, such as rock materialcoming out of a mine. They do not just do a surface measurement such asX-ray fluorescence and X-ray diffraction, but the analysis is deeplypenetrating, and can thus analyze large quantities of materials. Themost prevalent type of PGNAA analyzer is an on-belt conveyor analyzer,where all of the material on the conveyor belt is analyzed.

A commercially successful PGNAA analyzer was a chute-type of analyzer,as shown in FIG. 1 and described in 1986 U.S. Pat. No. 4,582,992 toAtwell et al. titled “Self Contained, On-line, Real-Time Bulk MaterialAnalyzer.” Coal or rock produce was sent down the chute, and thematerial passing through the system was analyzed by the system. U.S.Pat. No. 4,582,992 describes that the PGNAA system was self-contained.These chute systems were very expensive and installation was very costlyand difficult. This problem was solved with the development of on-lineconveyor-belt PGNAA analyzers. One cross-belt analyzer is shown in FIGS.2A and 2B, and described in 1995 U.S. Pat. No. 5,396,071 to Atwell etal. titled “Modularized Assembly for Bulk Material Analyzer”. Thesecross-belt systems were significantly easier to install, and fit verywell into the factory operations.

Since the first cross belt was developed, there have been a number ofinnovations to these cross-belt systems. The innovations have mainlyfocused on making the system easier to install and manufacture. Forexample, in U.S. Pat. No. 5,396,071 the belt analyzer was built inmultiple identical segments. Segments on the bottom were made from thesame mould, and segments on the top were made from a different mould.The central mould was modified to hold the source and detector. Thusthis innovation focused on making it easier to build and assemble theanalyzer. In Dec. 5, 2000 U.S. Pat. No. 6,157,034 to Griebel et al.titled “Flexible multiple-purpose modular assembly for a family of PGNAAbulk material analyzers,” side modules are used on the conveyor beltanalyzer such that the analyzer can be easily configured for differentsizes of conveyor belts. This innovation again made it easier forinstallation and adjustment for different belt sizes, and it simplifiedmanufacturing. In 2002, U.S. Pat. No. 6,657,189 to Atwell et al. titled“Maintaining Measurement Accuracy with Prompt Gamma Neutron ActivationAnalysis with Variable Material Flow Rates or Material Bed Depths,” thesystem was designed to algorithmically correct for errors as a result ofbed depth and flow rates. This patent was focused on reducing the errorthat varying flow rates and belt loading can cause in the PGNAAmeasurement. In W.O. Patent Application No. 2003056317 to Edwards et al.titled “Bulk Material Analyzer and Method of Assembly” discloses asystem consisting of detectors and source into a C shape such that thesystem can slide from the side onto the conveyor belt, and then theother side is added. The main purpose of this design was for ease ofinstallation, and also for simpler manufacturing of the analyzer.

In W.O. Patent Application No. 2008/021228 A3 to Atwell et al. titled“Bulk Material Assembly Including Structural Beams Containing Radiationshielding Material” focuses on making the system easier and lessexpensive to build, assemble and install. This patent applicationdescribes using structural beams that are filled with shielding materialto make it faster and easier to install the analyzer, and also reducethe system cost. Thus the design benefit was for easier installation andreduced costs.

Aug. 31, 2010 U.S. Pat. No. 7,786,439 to Harris et al. titled “DetectorApparatus,” discloses the idea of putting the multi-channel analyzer andthe detector in a housing that includes a temperature controlledassembly. U.S. Pat. No. 7,778,783 to Lingren et al. titled “Method andapparatus for analysis of elements in bulk substance” discloses a methodof stabilizing the spectra coming from the PGNAA analyzer.

Since the development of the first PGNAA on-belt analyzers, the designshave evolved, mainly with the focus of ease of installation and ease ofmanufacture. Modern PGNAA devices typically mount to the rails of aconveyor belt, do not require cutting of the conveyor belt, and can beinstalled and calibrated in a few days.

The performance of PGNAA analyzers has not improved dramatically overthe 25 years since the systems were first commercialized, as the systemsdeliver adequate performance for process control for most applications.

The industry with the widest adoption of PGNAA is the cement industry,where the equipment is used to monitor and control the raw material usedto make cement.

In the cement industry, there is growing demand for reducing energycosts by increasing the use of alternative fuels. Alternative fuels arematerials that can be burned in the cement kiln to provide heat content,and is a replacement for coal and oil. Alternative fuels are byproductsfrom industrial or commercial operations and include paint, metalcleaning fluids, electronic industry solvents, tires, fly ash, ricehulls, plastics and other industrial or municipal waste. Typicallycement plants can obtain these items at little or no cost, or in somecases are paid to burn.

For a cement plant to burn Alternative Fuels (AF), the AF generallyincludes three characteristics. The first characteristic is that the AFincludes little to no elements that negatively impact the cementmanufacturing process. For example, alternative fuels with too high alevel of chlorine are generally unacceptable for cement plantoperations. The Chlorine can turn into hydrochloric acid, and causeerosion in the kiln. Thus each AF end user has an upper limitspecification on the amount of Chlorine. The second characteristic isthat the AF must have a meaningful heat value, such that it is useful asa fuel. The third characteristic is that the material of the AF complieswith environmental regulations. The U.S. regulations essentially statethat to be acceptable, the AF cannot have contaminant levels greaterthan coal. This means that for AF to be acceptable for cement plants,elements such as mercury, arsenic, cadmium, lead, and other hazardouselements must be at a level that is at or below the level of coal.

Currently it is very expensive and time consuming in order to test andqualify new types of alternative fuels. There are companies thatspecialize in blending alternative fuel for cement plants. The vastmajority of these get a very specific and consistent type of feedstock,and they do not work with multiple different materials. Only a very fewcompanies blend varying stock of AF because of the difficulties andchallenges in ensuring that the material is suitable for plantoperations.

Another factor that makes this issue particularly challenging is thattesting AF for trace elements requires very low detection levels thatmay not possible with conventional PGNAA systems. Thus for receiving awide variety of alternative fuels, an expensive lab may be required toanalyze the AF. A lab can test only a very small sample, and thus maynot be a valid way of characterizing the AF.

SUMMARY OF THE DISCLOSURE

The PGNAA analyzer disclosed herein may deliver a significantly higherperformance than conventional PGNAA analyzers and is designed to deliverperformance suitable for analyzing alternative fuels for major mineralcontent that ultimately blends with the quarry rock and sand mineralcontent cement plants use such as Si, Al, Fe, Ca, Mg, S, K, Na, Mn, Ti,P—most as oxides) and detecting and measuring trace contaminants.Further, in embodiments disclosed herein, the PGNAA measurementinformation may be used to prepare a blend of AF with an elementalcomposition that is acceptable for plant operations. Additionally, themeasurement data provided by the analyzer may be used to prepare the AFto specific target heat content (such as BTLU/lb).

Conventional PGNAA systems may not be capable of measuring to thedetection level required to accurately measure trace elements in amaterial. The PGNAA analyzer disclosed herein includes a geometry thatmay increase the signal and performance of PGNAA systems, such as thesystem shown in FIG. 6. In embodiments, the PGNAA analyzer includes aflat bottom belt with vertical sidewalls that may deliver a higherefficiency than a conventional PGNAA analyzer because it may provide anoptimum geometry to locate arrays of detectors on all sides of thematerial. The PGNAA analyzer geometry may include a portion of thesource side when adequate neutron shielding placed between the sourceand the detectors on each side of the source. This geometry may not be agood fit for the type of conveyor belts common to the cement, coal andminerals industries, because these are ‘trough-shaped belts with 20 to45 degree angles.

In embodiments, the PGNAA analyzer disclosed herein includes modern highspeed electronics, which combined with this new geometry can improve themeasurement performance of PGNAA by a factor of 5 to 10× or more. Theexact performance improvement depends on other factors such as thedensity of the material, the elemental composition of the material(e.g., the percentage of hydrogen generally boosts the signal from allother elements due to hydrogen's strong moderation effect on the sourceneutrons), and so forth.

The PGNAA analyzer including modern high speed electronics may be ableto measure down to trace levels for such things as Mercury. Arsenic,Cadmium, and other trace elements.

The system with this or a similar geometry can also be used to analyzeraw material, coal, minerals, and other bulk material with significantlyhigher performance than conventional PGNAA systems. So this invention isnot limited to AF but to waste and any material put in or through thesystem.

In embodiments, this new high performance analyzer can be used in ablending process to blend AF so that it meets target composition. Theseembodiments include a method of blending the AF to meet targetspecifications such as target composition and heat content (BTU/lb) sothat it can be suitable replacement for coal, oil, and other fuels. Thisdesign is made to prepare the AF for the cement market, but the fuel canbe used in any market that can benefit from replacing coal, oil, andother fuels and for blending material to meet specific materialproperties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a chute analyzer.

FIG. 2A is a perspective view of a conveyor belt analyzer.

FIG. 2B is a side view of a conveyor belt analyzer.

FIG. 3 is a diagram of an analyzer where the material flows thorough theanalyzer. This configuration may be used for a static analyzer, or aslurry analyzer.

FIG. 4 is a schematic illustration showing conventional conveyor beltanalyzer.

FIG. 5 is a schematic illustration showing another conventional conveyorbelt analyzer.

FIG. 6 is a schematic illustration of one embodiment of a highperformance analyzer.

FIG. 7 is a schematic illustration of an alternate embodiment of thehigh performance analyzer of FIG. 6.

FIG. 8A is a schematic illustration of an alternate embodiment of thehigh performance analyzer of FIGS. 6 and 7.

FIG. 8B is a schematic illustration of an alternate embodiment of thehigh performance analyzer of FIGS. 6 and 7.

FIG. 8C is a schematic illustration of an alternate embodiment of thehigh performance analyzer.

FIG. 9 is a schematic illustration of a system for shredding, analyzingand blending alternative fuels.

FIG. 10 provides additional configurations for preparing alternativefuels.

FIG. 11 is a schematic illustration of a blending system.

FIG. 12 is a perspective view of a high performance PGNAA analyzer.

FIG. 13 is a functional block diagram of an analyzing system.

FIG. 14 is a functional block diagram of an analyzing system where thematerial is transported in a pipe.

FIG. 15 is a functional block diagram of an analyzing system where thematerial is transported in a air-slide.

DETAILED DESCRIPTION OF THE DRAWINGS

There have been several different types of PGNAA analyzers that havebeen developed over the past 25 years. These include a chute analyzershown in FIG. 1, a conveyor analyzer, shown in FIG. 2, and a pipeanalyzer where the material is analyzed either when it is not moving orwhen it is passing through the system, as shown in FIG. 3. These systemstake bulk material in solid or liquid form, and analyze the material.These systems and in particular the conveyor belt analyzer are used inthe coal, cement, and minerals industries.

By far the most predominant type of PGNAA analyzer is an on-beltconveyor analyzer, where the material is transported on a conveyor belt.A conveyor belt analyzer is shown in FIG. 4, where the neutron source404 is on the bottom, the belt 401 holds the material 402, and thedetectors 403 are located above the material 402. This is a typicalgeometry for a cement analyzer. Another configuration, shown in FIG. 5is where the conveyor belt is the same, but the neutron source is on thetop above the material, and the detectors are below the belt. This is acommon configuration for coal PGNAA analyzers. In a conveyor system, theconveyor belt is typically held in place using toughing belt idlerassemblies. The vast majority of toughing belt idler assemblies thathold the conveyor belt result in an angle 405 that is at a maximum of 45degrees.

FIG. 6 is a schematic illustration of one embodiment of a highperformance analyzer 100. In the embodiment illustrated, the PGNAAanalyzer 100 includes a conveying mechanism 108. The conveying mechanism108 includes a conveyor 101 with a flat bottom belt. The conveyingmechanism 108 may also include sidewalls 107 adjacent conveyor 101extending at least partially in the vertical direction. The Conveyor 101and the sidewalls 107 may form a detection zone 109. This detection zoneis the area that the material travels where the material is analyzed.

In some embodiments, the conveying mechanism may be rectangular shapedas show in FIG. 6 and may include substantially vertical sides 107. Inother embodiments, the conveying mechanism 108 may be trough shaped withthe sides 107 angled greater than 50 degrees from the horizontal and upto 130 degrees relative to the conveyor 101. In another embodiment, thesides 107 are angled from 40 degrees to 130 degrees relative to theconveyor 101. In another embodiment, the sides 107 are angled from 90degrees to 120 degrees relative to the conveyor 101. In still a furtherembodiment, the sides 107 are angled from 90 degrees to 120 degreesrelative to the conveyor 101.

The analyzer 100, as shown in the preferred embodiment in FIG. 6, andalternate embodiments in FIG. 7, FIGS. 8A, 8B, and 8C include locatingat least one neutron source 104 proximate the detection zone 109. In theembodiment illustrated in FIG. 6, the neutron source 104 is proximatethe conveyor 101 and below the conveyor 101. In the embodimentillustrated in FIG. 7, the neutron source is located above the detectionzone 107, opposite the conveyor 101. In the embodiment in FIG. 8C, theneutron source is located on the side of the conveyor, proximate thedetection zone 109, and the conveyor 101 acts as part of the sidewall ofthe analyzer 100.

As illustrated in FIG. 6, the detectors 103 are positioned proximate thedetection zone 109 along a side of the detection zone 109 adjacent thelocation of the neutron source 104.

Detectors 103 may be positioned on one side, or both sides of the sidewalls 107. As illustrated in FIGS. 7, 8A, and 8C, detectors 103 canadditionally be positioned opposite the neutron source 104 foradditional signal. As illustrated in FIG. 7, the neutron source 104 maybe above the material being analyzed. An alternate embodiment asillustrated in FIG. 8C is to place the source to the side of thematerial being analyzed. One or multiple detectors 103 can be used toincrease the overall signal from the analyzer 100. The detectors 103 canbe horizontal to the belt as shown in FIG. 6, or vertical, or anyorientation on the sides, which may increase the geometric efficiency ofthe PGNAA system. Arrays 105 of detectors 103 may also be used in thevarious locations for detectors described herein. In some embodiments,the analyzer 100 may also include an array of neutron sources 104.

The analyzer 100 may also include a controller 110. The controller 110may be configured to receive the signals from the detectors 103 and maybe configured to process the signals received to determine thecomposition of bulk material, such as an alternative fuel source and todetermine the amount of trace elements, such as contaminants that arewithin the composition. The controller 110 may also be configured tosort the bulk material based on its composition by directing the bulkmaterial to two or more locations based on the composition of the bulkmaterial, such as by directing a diverter gate into various positions todivert the bulk material into different directions. The controller 110may also be configured to determine the calorific value of the bulkmaterial, such as alternative fuel sources based on the measuredcomposition of the bulk material.

The configurations disclosed herein may situate the detectors 103 closerto the material that emits the gamma rays after the neutron source 104emits the neutrons into the material, which may improve the signal. Inembodiments, the source may be partially in the material. The exactlocation that is optimum may depend on the material, and the constraintsof the system.

In our preferred embodiment, the belt is flat or close to being flatwith substantially vertical sides. In an alternate embodiment, theconveyor belt system includes sides that are gradually rolled verticallyto form a tube. A circular array of detectors can be placed around thebelt. The sides, such as the vertical or gradually rolled sides, can bemade of different materials, but in the preferred embodiment they aremade of a material that can absorb and reflect the neutrons, such aspolyethylene.

Note that the sides do not have to be perfectly vertical, and the bottombelt does not have to be perfectly horizontal. Unlike other on-beltanalyzers that have the detectors on the top or the bottom, with thisdesign the detectors are on the side of the material under analysis. Thedetectors located on the substantially vertical sides of the belt mayplace the detectors and source closer to the analysis region, whilestill allowing for use of a conveyor mechanism.

There are other aspects to the design that are common to PGNAA systems.For example, the detectors are generally shielded from neutrons enteringthe detector. A combination of polyethylene, boron, and other materialsmay be used to shield the detectors from the neutrons. The system mayinclude biological shielding for radiation safety. The neutron source,if an isotope, typically has bismuth to block gamma rays emitted fromthe isotopic source. When a D-T generator is used, additional shieldingmaterial may be required for biological shielding, as well as to shieldthe detectors.

A typical analysis approach is shown in FIG. 13. In the preferredembodiment, the gamma ray spectra from each gamma detector is capturedby a Analog-to-digital board, and this data is analyzed by a processingmodule of the controller 110. In the embodiment illustrated in FIG. 13,the controller 110 is a computer. However there are many combinations ofdetector gamma ray processing configurations that are acceptable. Theresulting analysis can be displayed on a monitor, or provided over theweb. The computer would typically communicate with some other equipmentas part of this process. For example, a belt scale may be used to sendthe weight information to the analyzer, and this would be used in theanalysis. Similarly, a moisture meter, or other sensor can be configuredand used with the information. In the case of blending or screening ofmaterial, the computer may interface to blending software to control andguide the blending process. There are a number of external sensors thatmay be configured with the system, and there may be a number ofdifferent devices and systems that may take the data and informationfrom the system. Typically the resulting spectral data coming from thedetector is analyzed using library least squares analysis, ormultivariate analysis. However, there are other approaches that arepossible such as comparison of spectra, peak analysis of spectra,chemometrics, or other ways to extract the elemental information fromthe gamma spectra.

In this document, we refer to PGNAA. However, in our preferredembodiment, we are using a neutron generator as a source of neutrons,and Pulsed Fast Thermal Neutron Analysis (PFTNA) so that that it ispossible to extract additional measurement information such as thecarbon, oxygen, and nitrogen measurement information. PGNAA does notprovide these measurements, but PFTNA does provide these measurements.However, the technology can be Thermal Neutron Analysis (TNA), PFNA, andPFTNA, or other variations that are common in the industry. We refer toPGNAA, but it can be substituted for PFTNA, TNA, PFNA, or other neutronactivation analysis methods. In a preferred embodiment, we are using aconveyor belt to transport the material. This is because conveyor beltsare a very common method of transporting material. However, this caninclude other conveying means, such as a pipe, a pipe with a squarecross section, apron-chain conveyor, an air slide, or other means oftransporting the material. These transport methods can be configuredwith a similar geometry for higher performance. FIG. 14 shows thematerial being transported through a pipe 1407. The pipe would typicallybe of a low cross section material, such as a zirconium alloy. Thedetectors 1-3 are shown in an array, but they can be configured to becloser to the sides of the pipe 1407. As with other analyzer, there willbe shielding between the neutron source and the detectors. The sourcecan be pulsed or continuous neutron source. FIG. 15 shows an alternateembodiment where the conveyor includes an air-slide. In the embodimentillustrated, the conveyor includes an air chamber 1402 and a porousmaterial 1401 that allows air to pass to the main transport chamber1409. The main transport chamber 1409 includes sides 1403 adjacent theporous material 1401 and a top 1409. Top 1409 may extend from one side1403 to the other side 1403. Top 1409 is located opposite porousmaterial 1401 relative to the main transport chamber 1409 and thedetection zone 109. The main transport chamber 1409 encloses around thedetection zone 109. The air chamber 1402 is located next to the maintransport chamber 1409 and is separated from the main transport chamber1409 by the porous material 1401 The air from the air chamber travelsthrough the porous material 1401, and fluidizes the material beingtransported 102. The air slide is angled on a slight angle fromhorizontal to convey the material down the air slide. The conveyor/airslide section in the analyzer may also be made of material that has alow neutron cross section such as carbon fiber to minimize the signalfrom the air chamber structural material. Similarly the porous materialmay be composed of a material with a lower cross section material. Thedetectors are positioned to optimize the signal in the detection zone109. In FIG. 14, and FIG. 15, additional shielding material andmoderation material may be used between the neutron source and thematerial and detectors to optimize the signal from the material 102. Aswith the conveyor belt solution, the detectors may be located on thesides and adjacent to the neutrons source, or in the otherconfigurations and embodiments possible to those skilled in the art. Asthere are other methods of conveying material than conveyor belts, werefer to conveyor as a means of transporting the material, whether aconveyor belt, pipe, air slide or other conveying means.

We are using PFTNA in our preferred embodiment, because this producesmeasurements that are not possible with PGNAA. For example, PFTNA canmeasure carbon, oxygen, and nitrogen. Using these and PGNAAmeasurements, combined with external measurements such as the moistureor belt loading, the measurements can be used to estimate the calorificvalue (one expression is BTU/lb) of the AF.

Many different algorithms and equations are possible to estimate theBTU/lb or similarly to estimate the moisture content of the materialunder analysis. The Carbon, Oxygen, and Nitrogen measurements and othermeasurements in this equation are provided by the analyzer, as well aswith possible associated additional measurement equipment combined withthis system. An example of how to estimate the calorific value of thematerial is to use a linear combination of elements. This can be in theform of BTU/lb equalsA1*carbon_measurent+A2*oxygen_measurement+A3*hydrogen_measurement+AN*N_Measurement,where A1, A2, A3 coefficients, and AN*N_Measurement represents othercoefficients and measurements that are used to calculate the calorificvalue. This is just one example of calculating the calorific value. Manydifferent equations using the analyzer measurement values with possiblyadditional measurements from other equipment can be used to calculatethe heat value. We refer to heat value and Btu/lb. This refers to theheat content, often expressed as BTU/lb of the fuel. However, ourobjective is to produce a heat value that can be compared to coal orother fuels, whether this is in lbs, kg, an integrated value, or othermethods or units used to express the heating value of the material.

Various scenario and use models are possible with this configuration. Itmay be possible to just analyze the AF to ensure and verify that the AFhas suitable properties acceptable for use in a cement plant. Anotheruse model is to use the analyzer to blend the AF to provide a moreconsistent fuel.

Sorting followed by Gravimetric Blending utilizing individualweigh-feeders on each sorted stockpile that meter out a preciselycontrollable mass flow rate that when combined achieves a target blend.This can be done in many different ways. An example of a blending systemis shown in FIG. 9. A fork lift 901 takes the alternative fuels and putsthe material into a hopper 902. The AF is then conveyed 904 to ashredder 905. The AF is shredded, and then conveyed 906 to a coarseshredded pile 907. Magnets to pull off steel can be used in this process903, and at other locations. The AF is then transported, either on aconveyor or by fork lift to another hopper and conveyed to two-stageshredder 909. Thus the material comes out triple-shredded. The AFmaterial is then run through the analyzer 910. This analyzer providesthe elemental information of the triple-shredded Alternative Fuel. Thematerial then is placed in one or more piles 911 912. The composition ofeach pile is known from the measurement from the sensor 910. Thus thesepiles can be gravimetrically blended to get a more consistent product ora pile of unacceptable material can be sorted using a diverter 913. Thediverter 91 may be controlled by the controller 110. If there are anycontaminants or unwanted contaminants, a pile may be unacceptable foruse as AF 3. There are several ways to handle rejected material. Thefirst is to blend small amounts of rejected material with this withother piles that may have none or a near-negligible amount of undesiredtrace minerals, such that the overall blend is acceptable. The secondapproach is to have the pile hauled to a landfill.

An enhancement of this blending operation is to correct and adjust thematerial in the piles so that it has the required characteristics. Forexample, it is possible that the closer the characteristics of the AF isto a customer's requirements, and the more consistent the fuel, the morevaluable the fuel. If a specific BTU/lb is desirable, then blending canbe done such that the AF has the required BTU/lb. To blend the fuel to aspecific BTU content, AF with known high BTU material may be tripleshredded and added to one pile. Alternatively, a low BTU/lb pile can bemade with lower BTU/lb material. Using the average BTU/lb of each pile,a ratio of the two materials can be blended to give a specific BTU/lbvalue. A specific example can be used to clarify this. Assume one pileis 5000 BTU/lb, and the other pile is 10,000 BTU/lb, then a 50%/50%blend will result in a pile with a BTU of approximately 7,500 BTU/lb.Another approach is to blend while the material is being analyzed. Forexample, assume one pile has a 5,000 BTU/lb average, and then higher BTUmaterial is run and added to the pile. The material with the higherBTU/lb is sent through the triple shredding process, and then themeasured BTU information of this material is mass-integrated with theoriginal pile to build up a pile to a target BTU level. Using thisapproach, a pile can be built that has the required BTU/lb value.

Yet another approach is to take the shredded alternative fuel, andplacing this in a large layered pile. As a layer is placed on the pile,the composition of the AF material and location of the AF material isrecorded. Layer after layer of AF are built up on horizontal layers. Ifthe pile is layered horizontally, then the AF will bereclaimed/extracted vertically, and thus will represent an average forthe material. Prior to the extraction, corrective material is added tothe pile. For example, if a region in the pile has a low BTU/lb, thenhigh BTU/lb material is added at that location. This may be AF, oralternately it may be another fuel such as coal that is added. The highBTU/lb material is added to the location with the lower BTU. In thisway, the pile is built up such that it has a composition that iscontrolled and built to target specifications. Reclaiming of the pile isdone vertically, effectively averaging or integrating the material suchthat the resulting blend is consistent and at target specifications.

Two other blending approaches are illustrated in FIG. 10. In the topfigure, there are two or more piles of AF. One pile 1007 has high BTUmaterial, while another pile 1008 has lower BTU material. The materialis placed on the conveyor belt or transport mechanism, either by forklift in this case, or by other means such as silos. The material is thenconveyed to be shredded. A triple shredding of the material can be done1005 to ensure that the AF is well shredded, and in small pieces to aidin material transport and to help blending. There are cases where noshredding is required, but in this example the material is tripleshredded, and then put through the analyzer 910. The material is thenplaced in a pile 1006. By using the analyzer measurements for feedback,and using this information to adjust the amount of material 1008 and1007 that is used, this system can be designed to build a pile thatmeets specific target composition. The pile 1006 may be used, or may befurther mixed or blended to further reduce the fuel variability.

In the blending example in the bottom of FIG. 10, the material is takenoff the piles, shredded 1005 and run through the analyzer 910. Some formof diverter gate 913 can be used to build up different separate piles911 912, or alternately any material that has unwanted contaminants canbe sorted out 912. This process would be used in cases where there isthe potential of material that is not acceptable and that needs to beseparated from the rest of the AF.

The simplest way to use this system is to run the material through theanalyzer, whether it requires shredding or not, and to place thematerial in a pile or container. The analysis can then be used to verifythat the material is acceptable for plant operations, or the measurementinformation can be used to decide whether the material is notacceptable.

The blending of materials does not have to be limited to two materials,or just to waste or alternative fuels. Many different additives can beused. FIG. 11 shows a system where there are 7 additives that can beused to blend the material to a final composition. The material in thesilos 1101 to 1107 can be any material, such as AF, waste, iron,silicon, plastic beads, or other materials that may be used to blend topile 1108. The analyzer 905 is used to monitor the composition of thematerial and allows the operators to blend to a specific compositionand/or heat content of the pile 1108. This pile in turn may not be theend product, but may be mixed or blended, or used with other material.This approach has the benefit of being able to blend the pile to a rangeof values that is desirable for the blend pile 1108. This does not haveto be for the cement industry, it can be for any industry that canbenefit from combing the material in a controlled fashion to product thepile 1008. For producing a fuel, the silos might include one silo withhigh BTU/lb AF, and another silo with lower BTU/lb material, and this isused to control the output blend. Alternately, low Btu/lb material maybe added to the belt before or after the silos and the material in thesilos used to adjust the mixture. Note that we are using silos in thisexample, but these can be piles, or other means of providing therequired material. In addition, when we refer to BTU/lb, it is the heatcontent of the material on a weight basis, so can be expressed in manydifferent methods. As detailed in FIG. 11, the analyzer can be used toblend material to a specific composition that, in the case where one ofthe materials is waste or AF, can be used as a prepared blend that issuitable for use as a fuel.

The information from the analyzer does not have to provide all of therequired information for analysis. For example, the belt loading istypically provided by a separate sensor. The moisture reading may beprovided by an external moisture meter. Alternately, external sensorscan be added that can be used to improve the analysis results. Forexample, dual energy gamma detectors can be used to provide an absolutemeasurement of the organic and inorganic material in the AF. This inturn can be used to adjust the measurement information from theanalyzer. In some cases, there will be readings that are not suitablyaccurate from the analyzer. In this case, it may be necessary to useseparate measurement equipment to provide the required data andinformation. The analyzer does not have to provide all of the requiredmeasurement information, but the information it provides is used toensure that the material is acceptable as a fuel.

These blending approaches detailed above are not new. Raw materialblending has been done with PGNAA systems for over 20 years, and is inwidespread use throughout the cement industry. Extensive equipment,processes, and blending software is widely available that helps in theblending process. Any of the blending approaches that are now used forraw material blending, whether it is in discrete piles, done in silos,done in layers, or done in real-time using multiple ‘sweetners’, can beused to blend the alternative fuels to specific target blends. Inaddition, there are sites that blend AF. These sites use labs to dosample analysis of the AF to ensure no contaminants and to have anapproximate composition of the AF, and then the AF is mixed together.

There are many different ways of using the measurement data to calculatematerial heat value (expressed as BTU/lb in this patent). It is possibleto use the system measurement data and associated peripheral data toestimate the AF BTU/lb, and allow blending to specific BTU targets, orto verify that the material is acceptable for use as a fuel. Anotherbenefit of this new design of analyzer is that it is possible to measuretrace contaminants, and greatly improve the performance of theseanalyzers. Thus this has other applications such as measuring andcontrolling Mercury content of raw materials, measuring tracecontaminants in bulk material, controlling the amount of tracecontaminants in bulk material, blending using the measurementinformation, sorting using the measurement information, faster moreaccurate sorting of coal with different ash contents, and otherapplications that benefit from the improved system performance.

FIG. 12 is a perspective view of an embodiment of a high performancePGNAA analyzer 1200. As illustrated in FIG. 12, a conveying mechanism1208 may extend through the analyzer 1200. The conveying mechanism 1208may include a conveyor 1201 with sides 1207. Sides 1207 may be angledrelative to conveyor 1201 as disclosed herein.

Those of skill will appreciate that the various illustrative logicalblocks, modules, and algorithm steps described in connection with theembodiments disclosed herein can be implemented as electronic hardware,computer software, or combinations of both. To clearly illustrate thisinterchangeability of hardware and software, various illustrativecomponents, blocks, modules, and steps have been described abovegenerally in terms of their functionality. Whether such functionality isimplemented as hardware or software depends upon the design constraintsimposed on the overall system. Skilled persons can implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the invention. In addition, the grouping offunctions within a module, block, or step is for ease of description.Specific functions or steps can be moved from one module or blockwithout departing from the invention.

The various illustrative logical blocks and modules described inconnection with the embodiments disclosed herein can be implemented orperformed with a general purpose processor, a digital signal processor(DSP), application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor can be a microprocessor, but in thealternative, the processor can be any processor, controller,microcontroller, or state machine. A processor can also be implementedas a combination of computing devices, for example, a combination of aDSP and a microprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with theembodiments disclosed herein can be embodied directly in hardware, in asoftware module executed by a processor (e.g., of a computer), or in acombination of the two. A software module can reside in RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, harddisk, a removable disk, a CD-ROM, or any other form of storage medium.An exemplary storage medium can be coupled to the processor such thatthe processor can read information from, and write information to, thestorage medium. In the alternative, the storage medium can be integralto the processor. The processor and the storage medium can reside in anASIC.

The above description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the invention. Variousmodifications to the embodiments of the analyzer will be readilyapparent to those skilled in the art, and the generic principlesdescribed herein can be applied to other embodiments without departingfrom the spirit or scope of the invention. Thus, it is to be understoodthat the description and drawings presented herein represent a presentlypreferred embodiment of the analyzer and are therefore representative ofthe subject matter which is broadly contemplated by the presentinvention. It is further understood that the scope of the presentinvention fully encompasses other embodiments that may become obvious tothose skilled in the art.

1. A process of sorting alternative fuel materials into two or morelocations using an on-line nuclear based analyzer, the processcomprising: conveying the alternative fuel materials to the on-linenuclear based analyzer; quantitatively and non-destructively measuringan elemental composition of the alternative fuel materials includinghydrogen, carbon, and oxygen using the online nuclear based analyzer;determining a calorific value of the alternative fuel materials based atleast on the measured elemental composition; directing the alternativefuel materials with the calorific value within a first range to a firstlocation; and directing the alternative fuels material with thecalorific value within a second range to a second location.
 2. Theprocess of claim 1, wherein quantitatively and non-destructivelymeasuring the elemental composition of the alternative fuels materialsincludes conveying the alternative fuel materials through the on-linenuclear based analyzer on a conveyor with at least one neutron sourcelocated below the conveyor and detecting gamma rays emitted from thealternative fuel materials with at least one detector located adjacentthe conveyor.
 3. The process of claim 2, wherein quantitatively andnon-destructively measuring the elemental composition of the alternativefuels material includes detecting gamma rays emitted from thealternative fuel materials with an array of detectors located on theside of the conveyor.
 4. The process of claim 2, wherein quantitativelyand non-destructively measuring the elemental composition of thealternative fuels material includes detecting gamma rays emitted fromthe alternative fuel materials with an array of detectors located oneach side of the conveyor.
 5. The process of claim 4, whereinquantitatively and non-destructively measuring the elemental compositionof the alternative fuels material includes detecting gamma rays emittedfrom the alternative fuel materials with an additional array ofdetectors located above the conveyor.
 6. The process of claim 4, whereinconveying the alternative fuel materials through the on-line nuclearbased analyzer on a conveyor including sidewalls of fifty or moredegrees inclination to horizontal forming a substantially rectangularshape and positioning the detector arrays along the sidewalls.
 7. Theprocess of claim 1, further comprising blending the alternative fuelmaterials from the first location with the alternative fuel materialsfrom the second location to obtain a material with a predeterminedcalorific value.
 8. The process of claim 1, wherein quantitatively andnon-destructively measuring the elemental composition of the alternativefuels materials includes detecting trace amounts of contaminants.
 9. Ananalyzer for measuring an elemental composition of materials, theanalyzer comprising: a conveying mechanism including a conveyorextending in a horizontal direction, a first side wall extendingadjacent the conveyor, and a second side wall extending adjacent theconveyor opposite the first side wall forming a detection zone; at leastone neutron source located proximate the detection zone; and at leastone detector located proximate the detection zone and on a side of thedetection zone adjacent the neutron source.
 10. The analyzer of claim 9,further comprising a first array of detectors proximate the first sidewall including the at least one detector, and a second array ofdetectors proximate the second side wall; wherein the first array ofdetectors and the second array of detectors are configured to detecttrace amounts of elements including contaminants.
 11. The analyzer ofclaim 10, further comprising an array of neutron sources including theat least one neutron source located proximate the conveyor.
 12. Theanalyzer of claim 9, wherein the first side wall and the second sidewall are angled substantially perpendicular to the conveyor forming arectangular detection zone.
 13. The analyzer of claim 9, wherein thefirst side wall and the second side wall are angled from 50 degrees to130 degrees relative to the conveyor.
 14. The analyzer of claim 9,wherein the at least one neutron source is configured to emit fastneutrons, thermal neutrons, or a combination of both.
 15. The analyzerof claim 9, further comprising a processing module configured todetermine a calorific value of alternative fuel materials based at leaston the elemental composition measured by the at least one detector. 16.A process of analyzing bulk materials using an on-line nuclear basedanalyzer including at least one neutron source and at least onedetector, the process comprising: conveying the bulk materials to theon-line analyzer; conveying the bulk materials through the on-lineanalyzer on a conveying mechanism including a conveyor extending in ahorizontal direction, a first side wall adjacent the conveyor and asecond side wall adjacent the conveyor forming a detection zone;directing neutrons at the bulk materials using the at least one neutronsource located proximate the detection zone; and quantitatively andnon-destructively measuring an elemental composition of the bulkmaterials using the at least one detector located proximate thedetection zone and located on an adjacent side of the detection zone.17. The process of claim 16, wherein the process includes detectingtrace amounts of amounts of materials within the bulk materials usingthe array of detectors.
 18. The process of claim 17, whereinquantitatively and non-destructively measuring an elemental compositionof the bulk materials and detecting trace amounts of amounts ofmaterials within the bulk materials also uses a second array ofdetectors located proximate the second side wall.
 19. The process ofclaim 17, wherein directing neutrons at the bulk materials also uses anarray of neutron sources located proximate the conveyor.
 20. The processof claim 17, further comprising: directing the bulk materials to a firstlocation when trace materials of contaminants above a predeterminedlevel is detected; and directing the bulk material to a second locationwhen trace materials of contaminants below the predetermined level isdetected.
 21. The process of claim 20, further comprising blending thebulk material from the first location with the bulk material from thesecond location to include an amount of contaminants below a secondpredetermined level.